It is suggested that Christians are not to judge others. The most frequent New Testament passage referenced as a proof text is Matthew 7:1-2, “Judge not, that you be not judged. For with the judgment you pronounce you will be judged, and with the measure you use it will be measured to you” (ESV). There is, however, a difference between judging and being judgmental. 
Paul wrote to the Romans concerning being judgmental, “Therefore you have no excuse, O man, every one of you who judges. For in passing judgment on another you condemn yourself, because you, the judge, practice the very same things” (Romans 2:1). In a parallel passage to Matthew 7, Jesus said in Luke 6:37, “Judge not, and you will not be judged; condemn not, and you will not be condemned; forgive, and you will be forgiven.” Clearly, it is not God’s will for Christians to be a people with a condemning mentality.
It is also the case, however, Christians must judge others. The ability to judge another person is paramount to differentiating to knowing whom God has passed judgment and how to approach them with the love of the saving good news of Christ. Jesus put it this way: “I can do nothing on my own. As I hear, I judge, and my judgment is just, because I seek not my own will but the will of him who sent me” (John 5:30). Again in John he says, “Yet even if I do judge, my judgment is true, for it is not I alone who judge, but I and the Father who sent me” (John 8:16). Okay, Jesus judges but what about the common Christian?
Jesus said to his disciples, “Do not judge by appearances, but judge with right judgment” (John 7:24). A judgmental disposition is never correct because it only looks by personal opinion on the actions of others. Judging with correct judgment entails the same things Jesus said about his own ability to judge others. That is, discerning God’s judgment. This brings us back to Matthew 7. In Matthew 7:1-6 it is clearly hypocritical judgment that Jesus is preaching against.

Judge not, that you be not judged. For with the judgment you pronounce you will be judged, and with the measure you use it will be measured to you. Why do you see the speck that is in your brother’s eye, but do not notice the log that is in your own eye? Or how can you say to your brother, ‘Let me take the speck out of your eye,’ when there is the log in your own eye? You hypocrite, first take the log out of your own eye, and then you will see clearly to take the speck out of your brother’s eye. “Do not give dogs what is holy, and do not throw your pearls before pigs, lest they trample them underfoot and turn to attack you. (Matthew 7:1-6 ESV)

Clarke well wrote,

“These exhortations are pointed against rash, harsh, and uncharitable judgments, the thinking evil, where no evil seems, and speaking of it accordingly. The Jews were highly criminal here, and yet had very excellent maxims against it, as may be seen in Schoettgen. This is one of the most important exhortations in the whole of this excellent sermon. By a secret and criminal disposition of nature, man endeavors to elevate himself above others, and, to do it more effectually, depresses them. His jealous and envious heart wishes that there may be no good quality found but in himself, that he alone may be esteemed. Such is the state of every unconverted man; and it is from this criminal disposition, that evil surmises, rash judgments, precipitate decisions, and all other unjust procedures against our neighbor, flow.” (“Adam Clarke’s Commentary on the Bible” Adam Clarke, LL.D., F.S.A., (1715-1832)).

The condemning attitude of the Pharisees was atrocious. It is clear also that once introspection clears the log out of one’s own eye, he is capable of removing the speck in a brother’s eye. This enables one to judge with right judgment. Paul wrote to the Corinthian congregation, “The spiritual person judges all things, but is himself to be judged by no one. For who has understood the mind of the Lord so as to instruct him?” But we have the mind of Christ” (1 Corinthians 2:15-16). It is not with one’s own mind that the Christian judges others. We must look through the lens of Christ to see another person as God sees them. And even then, it is going to be a murky judgment because only God knows the heart within a man.
We all have something in our eye. So the question is, are we able to discern from the Word where a person is if we ourselves are not where we should be?
Donny Weimar